Use force when destroying VMs

There's no point in waiting several seconds for any guest utils to shut
    down the VM when we want to get rid of it as quickly as possible.  This
    also works around cases like

2016-12-12T10:33:22 [app] [W] Failed to destroy a compute foo (VMware) instance bar.example.com: ToolsUnavailable: Der Vorgang kann nicht abgeschlossen werden, weil VMware Tools auf dieser virtuellen Maschine nicht ausgeführt wird.
 | RbVmomi::Fault: ToolsUnavailable: Der Vorgang kann nicht abgeschlossen werden, weil VMware Tools auf dieser virtuellen Maschine
      nicht ausgeführt wird.
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/rbvmomi-1.8.2/lib/rbvmomi/connection.rb:61:in `parse_response'
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/rbvmomi-1.8.2/lib/rbvmomi/connection.rb:90:in `call'
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/rbvmomi-1.8.2/lib/rbvmomi/basic_types.rb:205:in `_call'
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/rbvmomi-1.8.2/lib/rbvmomi/basic_types.rb:74:in `block (2 levels) in init'
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/fog-1.34.0/lib/fog/vsphere/requests/compute/vm_power_off.rb:17:in `vm_power_off'
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/fog-1.34.0/lib/fog/vsphere/models/compute/server.rb:94:in `stop'
 | /usr/share/foreman/vendor/ruby/2.1.0/gems/fog-1.34.0/lib/fog/vsphere/models/compute/server.rb:107:in `destroy'
 | /usr/share/foreman/app/models/compute_resource.rb:155:in `destroy_vm'
 | /usr/share/foreman/app/models/concerns/orchestration/compute.rb:164:in `delCompute'
 | /usr/share/foreman/app/models/concerns/orchestration.rb:168:in `execute'

where VMWare misdetecs the Openvm tools status.